INTRODUCTION: This page is a summary
of motorcycle radios made by Motorola, Inc. up to approximately 1992. In
many cases, particularly with the later model radios, the dates of manufacture
are approximate since Motorola did not publish summaries of this information and
it is necessary to scavenge date information from manuals, and dates stamped on
examples of the equipment itself. It is a work in progress where changes
and corrections will be regularly made.

There are probably many models not shown here, mainly the
special production sets made for large customers. The California Highway
Patrol 1977 radios would be one example (covered in my CHP Radio pages.)
The radios shown here are the "off the shelf" regular models shown in
the standard Buyers Guides and sales literature. If you have photos of
sets not shown here, please share them and I will add them to the page.

Motorola was somewhat of a late starter in police radio,
not manufacturing an actual police radio receiver until 1937. As far as
can be determined, Motorola's first police motorcycle radio was not made until
the late 1940's, and was the two-piece FMTRU-5V "Dispatcher" series
set of 1947. During the 1930's and until 1947, police agencies used RCA,
GE, Comco, Air Associates, Link Radio (Vetric) and a variety of home-made
radios. Prior to 1946, virtually all commercially made police motorcycle
radios were one-way "receive only" sets. Please note that
Motorola was not the main manufacturer of police radios until well after WWII,
but became the predominant police radio make in the 1950's, including motorcycle
sets.

Motorcycle radios are more rare than the automobile
version; after WWII, there were perhaps 100 cars for every motorcycle in a
police force, hence the difference. By way of definition, throughout this
page, "Solocycle" refers to a 2-wheel motorcycle while
"Servicar" refers to a 3-wheeled cycle with utility box.

The photo below, believed to date from approximately 1945,
shows an early attempt to make a motorcycle radio from a car radio, before
Motorola actually sold such a product. This is a Motorola
"Police Cruiser" automobile type medium frequency one-way receiver
mounted on its back on the rear of a motorcycle, with a car radio antenna
installed on the housing front (now top) cover. This installation could
hardly have been very reliable, since it is expected that vibration would have
caused the tubes to leave their sockets and the adjustments to quickly go awry.
It would also not have been even slightly weatherproof.

Photo courtesy of Scott Cacciamani, Staten
Island, NY

DISPATCHER Series (1947-53)

Motorola's first one-piece car type FM two way radio was
the "Dispatcher" model, introduced in 1947 as an "economy"
radio, manufactured through approximately 1952. This model was also
offered in a motorcycle version, accomplished by separating the internal chassis
units so that the transmitter and power supply chassis was on one side of the
rear wheel in its own box, and the receiver was on the other side. The
appearance is exactly like that shown below for the "Research" radios.
This was a 6 Volt vibrator powered radio with a 10 Watt transmitter. The
"Solocycle" control head consisted of a standard hammertone gray
mobile speaker housing, but with volume and squelch knobs placed on top.
The microphone jack was extended separately from the control cable and mounted
underneath the fuel tank (much later radios would feature the microphone jack on
the head itself.) The microphone was a special Shure CB-12 series mounted
on a convenient spot on the fuel tank area or the handlebars, in a rubberized
claw-shaped holder. There was no hang-up stud on the rear of the
microphone.

There was also a "Servicar" radio package and
control head, where the radio package was in a single housing as shown below and
mounted in the trunk of the three-wheeler. The Servicar control head is
shown below under "Research" models, as the 5V Dispatcher and Research
radios shared the same control heads (but not the same cables.) The Dispatcher
5V series was made in low band and high band versions, although it was initially
offered only in a VHF high band configuration to accommodate the FCC's 1946
edict that new police radio systems were to be issued high band licenses absent
a showing of need to still use low band.

Shown below is the typical first generation Dispatcher
motorcycle microphone, a Shure CB-12 series. Note that the
"hang-up" stud is not featured on the rear, as this style microphone
was carried in a "claw" type mounting. The discoloration around
the push-to-talk button is the remains of the cement which once held a thin
rubber membrane designed to keep weather out of the interior of the microphone.

RESEARCH Series (1953-57)

The original Dispatcher 5V series had quickly become
obsolete and by early 1953 was replaced by the "Research Line" M31-1
and M33-1 radios, later re-numbered M31-G and M33-G. Using the same sort
of saddlebag-style black steel box housings, the Research sets used the new
"Unichannel" transmitter and receiver chassis. All chassis were
separate units in the Unichannel model, so in Solocycle applications one
saddlebag box held the transmitter and power supply, while the other contained
the receiver only. This Research Line motorcycle radio was also made in a
one-piece case as a Servicar radio for three-wheeled cycles, and the control
head for the Servicar was a flat faced box which mounted through a large hole in
the rear box of the three-wheeled cycle, facing the rider's left side from
behind. See photos below. The initial Research Series was replaced in 1955 with the
"Twin-V" equipment. The Twin-V name referred to the car radios
which were marketed to deal with the American auto industry's change-over to 12
Volts, being capable of functioning on either 6 or 12 Volts depending upon the
cables used. Motorcycles remained 6 Volt until well into the 1960's, so the
Twin-V name was somewhat of a misnomer when applied to that equipment.
Some of the Research Line mobiles also offered this feature, so it wasn't
anything new with the Twin-V series. The Twin-V series is almost identical
to the Research, except for new control head and microphone styles as seen below
in the Twin-V section.

Note in the photo below that the microphone is
held in a bracket at the fuel tank, and that the microphone connector is at the
end of a cable on a small bracket.

Shown below is a rather shabby Servicar
head. Note that the knobs are missing as is the key switch. The hole next to the
volume control would have been covered with a plug and would have contained the
rare two frequency switch where used. The larger hole contained a key
switch similar to a Briggs & Stratton ignition switch. This head was used on
both the FMTRU-5V and the Research S31-1 and S33-1 Servicar sets. This
head mounted on the left forward side of the rear box of the three-wheeler, the
microphone hanging on the side of the fuel tank.

Shown below is this head mounted on a Servicar, taken in
1954. Note that the Servicar radio package was physically identical to the
automobile mount radio version, not two-piece as the Solocycle was.

TWIN-V Series (1955-1960)

As mentioned above, the "Twin-V" was a slightly
upgraded replacement for the Research Line but basically the same radio.
The Twin-V, like the Research sets, was offered in a two-piece saddlebag
mounting scheme (models M31GGV and M33GGV) and also as a one-piece Servicar unit
(such as the S31GGV-1100 series radios.) The Twin-V used a new style
control head, still basically a mobile speaker housing, but now matching the
Twin-V car radio speaker design, with two-tone paint. The microphone
continued to be mounted separately. Unlike the FMTRU-5V and Research Line
radios, the Twin-V series used the same handlebar-mounted control head for
either the Solocycle or the Servicar sets. The Twin-V name was actually
applicable to the car type mobile radios, which were called that to capitalize
on the feature of being able to be used on either 6 or 12 Volt vehicles by
selection of the appropriate cable (even though "Research" car mobiles
could also be ordered as 6/12 V capable.) Motorcycles remained 6 Volt
until into the 1960's. The circuitry of the Twin-V chassis is almost the
same as that of the Research Line shown above, other than some component
improvements. The Twin-V was the last all-vacuum-tube motorcycle radio by
Motorola, as well as the last one using a vibrator type power supply.
Motorola continued to use the name "Research Line" well into the
1960's, so the use of the term "Twin-V" here is a bit confusing.
I refer to the last generation vacuum tube radio as the "Twin-V"
because the manual for it refers to it as such.

Note that the radio shown mounted in the photo below is
actually a Research series, used in the Twin-V manual because the two are so
similar, apparently to cut photo costs. The Twin-V toggle switch for
"standby-operate" is in a different place on the Twin-V, see the photo
of the California Highway Patrol Twin-V box below for an example of this.

The high band (150 MHz) Twin-V boxes do not have the bulge
on the rear featured on the low band (30-50 MHz) radios, which houses the
antenna loading coil assembly.

MYSTERY RADIO:The
radio shown below is a mystery set. Note the bizarre antenna, called a
"DDRR" in the industry (directional discontinuity ring radiator.)
The motorcycle was an in-service Anaheim Police (California) unit in 1966.
The control head appears to be a Twin-V style head because of the separate mike
hang-up arrangement, color scheme and cable exit out the back, but the radio is
a one-piece unit mounted in what appears to be a steel box above the rear
fender, where the antenna is mounted. This radio was made by Motorola for
cities in Orange County, California. The antenna, not a Motorola item, was
apparently produced locally by a Los Angeles area manufacturer. Anecdotal
evidence suggests that possibly the Twin-V radio may have been available in a
one-piece over-the-fender style box, on special order, which would explain this
oddity (except for the antenna.) Any information about this strange set
would be appreciated!